Abducens nerve enhancement demonstrated by multiplanar reconstruction of contrast-enhanced three-dimensional MRI

Detailed imaging of abducens nerve anatomy using contrast-enhanced 3D-TOF MR angiography

PURPOSE

Cranial nerves (CNs), particularly CN IV and VI are difficult to visualize with conventional MRI techniques, particularly within the cavernous sinus region. The aim of this study was to evaluate the capacity of high-resolution contrast enhanced 3D time-of-flight (TOF) MR angiography using new generation 3 T imaging technology to provide detailed visualization of CN VI anatomy, particularly within the cavernous sinus and petroclival regions.

METHODS

Two neuroradiologists conducted bilateral evaluation of CN VI visibility in 23 patients for nerve segments located in the petroclival segment (dural cave and Dorello's canal), and three divisions of the cavernous sinus. All images were collected using contrast enhanced TOF MR angiography using a new generation 3 T machine.

RESULTS

Of the CN VI segments assessed, average visibility of CN VI was best achieved in Dorello's canal. Overall visibility of CN VI within the regions inspected was best achieved in the axial view, with the exception of the dural cave, which was best assessed using the coronal view. We also identified strong agreement in assessment of nerve visibility between the two reviewers. We also identified a putative CN6 duplication and a small schwannoma, highlighting the fidelity of our approach.

CONCLUSION

Contrast enhanced 3D TOF MR angiography can visualize CN VI anatomy, particularly within the petrocavernosal region and cavernous sinus with simultaneous visualization of arterial and venous structures. This cannot be easily achieved using traditional MRI techniques. This imaging technique might be used with new generation machines to evaluate CN VI anatomy and pathologies within the petrocavernosal region and cavernous sinus, especially relating to vascular pathologies.

[A case of atypical Tolosa-Hunt syndrome with a contrast enhanced lesion of the oculomotor and trigeminal nerves on MRI]

A 30-year-old woman was admitted to our hospital because of intractable orbital pain and ptosis on the left side. On admission, she had left oculomotor, ophthalmic and maxillary nerves palsy. MRI revealed a contrast enhanced lesion of the left oculomotor and trigeminal nerves through the covernous sinus and orbita. We diagnosed her condition as Tolosa-Hunt syndrome. The orbital pain was resolved within 48-hours by the pulse therapy with intra-venous methylpredonisolone. The cranial nerve palsy was gradually improved, but never reached complete remission. The left oculomotor and trigeminal nerves also remained enhanced on MRI until 200 days from the onset. Although there have been few reports to demonstrate the contrast enhancement of cranial nerves in Tolosa-Hunt syndrome, these MRI findings may be a specific indicator of the pathological process.

Isolated oculomotor nerve palsy following minor head trauma : case illustration and literature review

Isolated oculomotor nerve palsy (ONP) attributable to mild closed head trauma is a distinct rarity. Its diagnosis places high demands on the radiologist and the clinician. The authors describe this condition in a 36-year-old woman who slipped while walking and struck her face. Initial computed tomography did not reveal any causative cerebral and vascular lesions or orbital and cranial fractures. Enhancement and swelling of the cisternal segment of the oculomotor nerve was seen during the subacute phase on thin-sectioned contrast-enhanced magnetic resonance images. The current case received corticosteroid therapy, and then recovered fully in 13 months after injury. Possible mechanism of ONP from minor head injury is proposed and previous reports in the literature are reviewed.

Recent developments and future directions in Guillain-Barré syndrome

Guillain-Barré syndrome (GBS) encompasses a spectrum of acquired neuropathic conditions characterized by inflammatory demyelinating or axonal peripheral neuropathy with acute onset. Clinical and experimental studies in the past years have led to substantial progress in epidemiology, pathogenesis of GBS variants, and identification of prognostic factors relevant to treatment. In this review we provide an overview and critical assessment of the most recent developments and future directions in GBS research.

Tolosa-hunt syndrome associated with cytomegalovirus infection

We herein present the case of a 38-year-old woman with left-sided oculomotor paralysis with ocular pain that developed after a respiratory infection. Her serum was positive for IgM against GM2 and GalNAc-GD1a gangliosides and cytomegalovirus. Thin-slice magnetic resonance imaging revealed enhanced abnormal tissue located primarily in the superolateral part of the left-sided cavernous sinus, which corticosteroids subsequently obscured with immediate resolution of the patient's ocular symptoms. These clinical features were consistent with those of Tolosa-Hunt syndrome (THS). Our findings in the present patient suggest that cytomegalovirus may provoke granuloma formation in the cavernous sinus, as reported in other various organs, thereby leading to the development of THS.

Multiple cranial nerve enhancement on MRI in primary Sjögren's syndrome

A 77-year-old man showed bilateral abducens palsies and multiple cranial nerve enhancement on magnetic resonance images (MRI) and aseptic meningitis. He had xerophthalmia and xerostomia. Serum anti-SS-A and anti-SS-B antibodies were present. He had Sjögren's syndrome (SjS) and corticosteroid therapy ameliorated the symptoms. The cranial nerve enhancement and the cerebrospinal fluid findings were normalized. In patients with SjS, there have not been any reports of multiple areas of cranial nerve enhancement on MRI. We propose that in this case the aseptic meningitis and subsequent lymphocytic infiltration to the cranial nerves contributed to the multiple cranial neuropathy and multiple cranial nerve enhancement on MRI.

Efficiency of corticosteroid treatment in resolution of bilateral abducens paralysis after head trauma

A rare case of posttraumatic bilateral abducens palsy is presented. A 17-year-old male patient referred to our clinic because of complaints of diplopia, difficulty in opening his mouth, pain in the face, dyspnea, and chest pain after head trauma from a motor vehicle accident. The patient was not able to abduct eyes bilaterally, and diplopia occurred in the lateral gaze. All other extraocular movement was intact. He also had a mandibular fracture and bilateral pneumothorax. Computed tomography scan of the cranium showed no intracranial or extracranial hemorrhage, no mass effect, and no edema. No abnormalities were seen in the orbits, sinuses, skull base, and calvarium. For the treatment of sixth cranial nerve palsy, we applied corticosteroid therapy and waited for spontaneous recovery. During follow-up, at 3 months after discharge, he showed marked improvement in his ocular mobility and alignment without any residual limitation of abduction bilaterally. A bilateral sixth nerve palsy is rarely seen after a head trauma without cranial pathologic findings, and corticosteroid therapy may have beneficial effects during treatment besides spontaneous resolution.

Imaging evaluation of cranial nerves 3, 4, and 6

Neuropathies of the oculomotor, trochlear, and abducens nerves may present with isolated or complex neurologic findings. An understanding of the anatomy of these cranial nerves as they traverse the brainstem, basilar cisterns, and cavernous sinus on their way to the orbit can assist in localizing the suggested site of pathology and help to focus imaging protocols. Differential diagnostic possibilities for specific anatomic locations are reviewed.